Place racks in the upper and lower thirds of your oven and preheat the oven to 400 degrees F. Bake bacon according to these directions for Baked Bacon. Let cool, then chop or crumble into bits.
Spray 18 total cups in two standard muffin tins with nonstick spray.
Meanwhile, place the cream cheese pieces in a wide microwave-safe bowl. Microwave in 10 second bursts until the cream cheese is very soft and melty but not so hot that it is steaming.
Stir in cheese cream, garlic powder, black pepper, and oregano until well combined.
In a separate large mixing bowl, combine the spinach, feta, Parmesan, and chopped bacon with a fork, breaking apart the spinach. Scrape the cream cheese mixture on top of the spinach mixture, then stir the ingredients until well combined. Taste and adjust seasoning as desired.
Unfold the first sheet of pastry on a lightly floured surface and gently roll to remove any creases.
Cut the pastry sheet into 9 even squares. Line the wells of the muffin pan with the pastry squares so that the center is pressed on the bottom of the muffin cups and the corners over hang. If needed, stretch the squares to be a bit larger so that they extend all the way up the sides. With a spoon or small scoop like this one, portion the spinach filling by heaping tablespoons and place it in the center of each muffin cup, dividing it evenly among the 18 cups.
Bring the four points of each puff pastry square together towards the center so that they cover the filling, then lightly press them together in the middle.
Bake the puffs, one muffin tin on each rack, for 21 to 24 minutes, until puffy and deeply golden, switching the pans' position on the upper and lower racks halfway through.
Allow to cool for 10 minutes, then run a knife carefully around the edges to gently loosen them. Transfer to a wire rack. Serve warm or at room temperature.
